In processes that use a chemical liquid for a semiconductor manufacturing device, a chemical liquid supply system such as that in Patent Reference 1, for example, has been disclosed for coating a specified volume of a chemical liquid such as photoresist on semiconductor wafers. In this chemical liquid supply system, a flexible tube is present in a chemical liquid passage within a pump, and an elastically deformable bellows is provided on the outside of the flexible tube. A small bellows member and a large bellows member of differing internal diameters are provided in an aligned manner in the axial direction of the flexible tube in the bellows, and an incompressible medium is inserted in the space between the bellows and the flexible tube. Moreover, a motor actuator incorporated in a unitary manner with the pump causes the small bellows member to expand and the large bellows member to contract, decreases the volume of the flexible tube via the incompressible medium, and discharges the chemical liquid. Conversely, the motor actuator causes the small bellows member to contract and the large bellows member to expand, increases the volume of the flexible tube via the incompressible medium, and takes in the chemical liquid.
The motor actuator, however, was expensive and made the configuration of the system complex. Additionally, the amount of heat generated during operation increased, and this heat posed the risk of damaging semiconductor wafers positioned near the pump for receiving the chemical liquid supplied from the pump.
A technology for resolving the above-mentioned problem is disclosed in Patent Reference 2, for example. In this chemical liquid supply system, a diaphragm is used that divides a pump chamber for filling the chemical liquid into the pump and a pressurization chamber (operating chamber). In order to decrease the volume of the pump chamber so that the chemical liquid is discharged, air is supplied under pressure from a regulator to the pressurization chamber of the pump, and the diaphragm is deformed toward the side of the pump chamber. Conversely, in order to increase the volume of the pump chamber so that the chemical liquid is taken in, the air pressure within the pressurization chamber of the pump is decreased with a regulator, and the diaphragm is deformed toward the side opposite the pump chamber. In this situation, a decrease in the air pressure alone cannot adequately bring about an amount of deformation (amount of operation) of the diaphragm toward the side opposite the pump chamber. Therefore, a spring is provided in the pump, and the diaphragm is impelled toward the side opposite the pump by the spring so that the diaphragm is deformed toward the side opposite the pump chamber.
No motor that generates a large volume of heat is used in this chemical liquid supply system, so the risk of heat-related damage to semiconductor wafers is eliminated. A spring for deforming the diaphragm toward the side opposite the pump chamber, however, is provided in the pump, which presents a problem when the pump is to be downsized.    Patent Reference 1: Japanese Patent Application Publication H10-61558    Patent Reference 2: Japanese Patent Application Publication H11-343978